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Steel V Wheels - need (inexpensive) rail ideas

Discussion in 'Concepts and Ideas' started by orangezero, Jun 3, 2015.

  1. orangezero

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    I've been looking at options for railing for steel v wheels such as rm2zz or rm2-2rs. I realize aluminum rails are not the way to go, but most case hardened steel rails are super expensive. PBC linear seems to be the cheapest option, but still expensive. They have rail on amazon and zoro. I've gotten a quote from them about their steel rail IVTAAB series, but that is around $3 per inch. Takes out a lot of the hard work of alignment, though.

    So, has anyone used v-slot with steel wheels, and adding a 0.75 or 0.5o inch steel angle between the wheel and v-slot? Or would it be slightly better to use cold-rolled square mounted at a 45degree angle in the slot to make a rail (closer to the bottom left photo, but with square rather than angle)? I've heard cold rolled would have slightly tighter tolerances (fyi, I'm thinking on order of 0.01mm precision as a goal rather than 0.0001mm, at least on my machine).

    Could either option work via jbweld? Or perhaps some properly placed screws? I could see gravity holding in the top I don't think I've seen too many options.

    The angle iron idea would be similar to the photo second from the left on the bottom. The v-slot would then be underneath, and the same thing would repeat on the bottom.
    455513798_126.jpg
    The reason I ask, is because two 1000mm and one 1500mm 2060 vslot pieces, along with the six steel angles, would still be around half the cost of several other options I've looked into. In some cases, 10x less...

    Would something like this "work" but be an order of magnitude away from a proper linear rail and cause lots of problems?

    This is a hobby, so don't want to go overboard on one part of the system (nema23 motors, thinking 9mm gt2 belts). Just for more information, I already have two 1000mm and a 1500mm 6090 extrusion I picked up a while ago, so I'm looking for something to bolt to those. I'm not excited about drilling directly into the extrusion, so a linear rail like PBC sells would still need another piece to offset the rail (more cost). My thought was butting vslot to the 6090 is easier to do.

    Thanks for any thoughts.
     
  2. Rick 2.0

    Rick 2.0 OpenBuilds Team
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    JBWelding 1/4" square bar on the diagonal would probably be the cheapest. I can't say as anyone has tried it though.

    Rail Suggestion.jpg
     
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  3. Joe Santarsiero

    Joe Santarsiero OB addict
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    I don't think you're going to see 0.01mm tolerance from the extrusion or over the length of steel. When combined the tolerances may stack in some spots.
    Ricks idea with JB weld or an epoxy seems like a good one. You can float the steel and make adjustments before it sets. Cncrouterparts has a system called v-con that uses bar stock and specially made clamp brackets. It gets costly though. http://www.cncrouterparts.com/v-con-linear-motion-parts-c-47_50.html
    You can find hardened v-rail. That is somewhere around $1 an inch.
     
    #3 Joe Santarsiero, Jun 3, 2015
    Last edited: Jun 6, 2015
  4. orangezero

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    Thanks for the responses. I should have clarified, the 0.01mm tolerance was a random guess to get a sense of perspective (cnczone people sometimes like to unknowingly compare $1000 machines to $20,000 machines). I'm not even sure of the tolerances of the vslot itself, but I'm guessing it is no where near the tolerances for most of the linear stuff I'm looking at. Precision isn't cheap.

    The cheapest v-rail I can find is the 0.437in tall stuff from zoro/grainger/amazon from PBC. It is about $22 for a 36in piece, but you'd need two for each carriage. The 48in was $31. But this also requires quite a bit of alignment, drilling, screwing...

    I've only had regular extrusion at this point, so always eliminated this as an option. The v-slot at least makes it plausible.

    That being said, I've seen someone do similar to Rick 2.0's idea, but had screws to hold it down. The screw heads just missed the v-wheel. Not sure of the type of head. 20mm extrusion doesn't really provide a lot of room to work with.

    I've been brainstorming this a while. It is amazing how many flat bar/angle iron parts are almost workable but just don't have two opposing 45 degrees angles like we need. 3in angle iron would work, but I'm guessing it has its own problem. Plus, I already own extrusion...

    Thanks again.
     
  5. getoffmyland

    getoffmyland Well-Known
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  6. Patrick Walls

    Patrick Walls Well-Known
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    check with cncrouterparts, they have set up using square stock at right angles with clamps to hold the bar in place.
    Pat
     
  7. Mark Carew

    Mark Carew OpenBuilds Team
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    You can also use steel V wheels on round bar if the diameter is small enough.
    Mark
    EDIT: whoops already been said :)
     
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  8. orangezero

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    I bought some cold roll 5/16in square solid rod for my x and y axis, laying them at a 45 degree angle in regular old extrusion. It seems solid enough for me to order a few more steel wheels. Ideally, I'd cut a V channel in a piece of aluminum and place the cold roll on that, but resting them on the slot seems to be acceptable to me so far. Or, I'd just buy those parts from cncrouterparts, but I'm cheap.
     

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